Block copolymers near the microphase separation transition. 4. Dielectric spectroscopy

Quan, Xuebo; Johnson, Guy; Anderson, E. W.; Bates, Frank S.

doi:10.1021/ma00195a076

Cited by 49 publications

(27 citation statements)

References 5 publications

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“…Quan et al (24) used dielectric spectroscopy to study diblock copolymers on the basic of 1,4-polybutadiene/ 1,2-polybutadiene and their respective homopolymers. The microphase-separated block copolymer showed four transitions: two glass transition peaks and two shoulders corresponding to the ␤-transitions of the homopolymers.…”

Section: Investigation Of Morphology Formationmentioning

confidence: 99%

Investigation of morphology formation in SBS block copolymer/homopolystyrene blends

Huy

Adhikari

Lüpke

et al. 2004

Polymer Engineering & Sci

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Polymer blends comprising a polystyrene‐block‐polybutadiene‐block‐polystyrene (SBS) block copolymer and atactic homopolystyrene (hPS) were investigated using injection molded and solution cast samples. The morphology of the materials was studied by means of transmission electron microscopy (TEM) and scanning force microscopy (SFM). Dynamic mechanical analysis (DMA) was used to characterize the phase behavior and the morphology formation of the block copolymer as well as of the SBS/hPS blends. The glass transition temperatures seem to strongly depend on the homogeneity of the corresponding phases. A distinct difference was found between the morphologies of the blends prepared by different methods. While the SBS block copolymer always shows a lamellar morphology in injection molded or as‐cast samples, the injection molded blends show a disturbance in the morphology consisting of alternating layers. In contrast, in the case of as‐cast samples, added hPS forms polystyrene domains dispersed in a matrix of the pure block copolymer. Regarding the change in the glass transition temperature, in the effective volume and in the interfacial volume obtained from DMA curves, the morphology formation of the injection molded samples (pure SBS block copolymer and the corresponding blends) was investigated. Two different structural models for the blends are proposed. Polym. Eng. Sci. 44:1534–1542, 2004. © 2004 Society of Plastics Engineers.

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Section: Investigation Of Morphology Formationmentioning

confidence: 99%

Investigation of morphology formation in SBS block copolymer/homopolystyrene blends

Huy

Adhikari

Lüpke

et al. 2004

Polymer Engineering & Sci

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“…It has been reported in the literature that the homopolypeptide of the protected tyrosine has a Tg value at 41 °C [46]. Dielectric measurements for the PB1,4 and PB1,2 segments indicated that the α-relaxation is located at −78 °C and 19 °C, while a secondary transition at −26 °C for the PB1,2 is attributed to the rotation of the side groups [57]. In Figure 8 Finally, it should be mentioned that the processes related to the protected polytyrosine are found at higher values for the PB-containing samples, probably due to the chemical structure of the polybutadiene, which signifies an important role in the conformational changes.…”

Section: Dielectric Spectroscopymentioning

confidence: 85%

“…It has been reported in the literature that the homopolypeptide of the protected tyrosine has a T g value at 41 • C [46]. Dielectric measurements for the PB 1,4 and PB 1,2 segments indicated that the α-relaxation is located at −78 • C and 19 • C, while a secondary transition at −26 • C for the PB 1,2 is attributed to the rotation of the side groups [57]. In Figure 8 cating segmental changes in the polypeptide related to secondary structures mixing with the polydienes and the α-relaxation.…”

Section: Dielectric Spectroscopymentioning

confidence: 87%

Synthesis, Characterization and Structure Properties of Biobased Hybrid Copolymers Consisting of Polydiene and Polypeptide Segments

et al. 2021

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Novel hybrid materials of the PB-b-P(o-Bn-L-Tyr) and PI-b-P(o-Bn-L-Tyr) type (where PB: 1,4/1,2-poly(butadiene), PI: 3,4/1,2/1,4-poly(isoprene) and P(o-Bn-L-Tyr): poly(ortho-benzyl-L-tyrosine)) were synthesized through anionic and ring-opening polymerization under high-vacuum techniques. All final materials were molecularly characterized through infrared spectroscopy (IR) and proton and carbon nuclear magnetic resonance (1H-NMR, 13C-NMR) in order to confirm the successful synthesis and the polydiene microstructure content. The stereochemical behavior of secondary structures (α-helices and β-sheets) of the polypeptide segments combined with the different polydiene microstructures was also studied. The influence of the α-helices and β-sheets, as well as the polydiene chain conformations on the thermal properties (glass transition temperatures, thermal stability, α- and β-relaxation) of the present biobased hybrid copolymers, was investigated through differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and dielectric spectroscopy (DS). The obtained morphologies in thin films for all the synthesized materials via atomic force microscopy (AFM) indicated the formation of polypeptide fibrils in the polydiene matrix.

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“…Because 1,2‐PB and 1,4‐PB have very different glass transitions (272 and 178 K, respectively), their different dynamics could in principle be apparent in this case as a second glass transition. However, two glass transitions have been only being reported for block copolymers of 1,2‐PB and 1,4‐PB in the case of microphase separation . This low‐frequency shoulder cannot be attributed to the presence of the ionomer moiety, because it is also present in the neat PB.…”

Section: Resultsmentioning

confidence: 99%

Dynamics of novel polybutadiene ionomers

Hemmer

Mason

Casalini

2019

J Polym Sci B Polym Phys

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The dynamics of novel ionomers based on a lowmolecular-weight polybutadiene with zinc acrylate moieties were investigated as a function of the number of ionic bonds by using a combination of calorimetry, dielectric broadband spectroscopy and rheology. We find that the ionic bonds have profound effects on the mechanical properties, including the introduction of a sol-gel transition. However, all techniques consistently indicate that the segmental dynamics of the polymer chains remain largely unaffected, and only very small changes in the glass transition were observed.

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Block copolymers near the microphase separation transition. 4. Dielectric spectroscopy

Cited by 49 publications

References 5 publications

Investigation of morphology formation in SBS block copolymer/homopolystyrene blends

Investigation of morphology formation in SBS block copolymer/homopolystyrene blends

Synthesis, Characterization and Structure Properties of Biobased Hybrid Copolymers Consisting of Polydiene and Polypeptide Segments

Dynamics of novel polybutadiene ionomers

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